Инструкции По Установке для 3com S7906E

 

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A switch does not forward an MLD report through a non-router port. This is because if the switch 

forwards a report message through a member port, all the attached hosts listening to the reported IPv6 

multicast address will suppress their own reports upon receiving this report according to the MLD report 

suppression mechanism for hosts, and this will prevent the switch from knowing whether the reported 

multicast group still has active members attached to that port.  

For the MLD report suppression mechanism of hosts, refer to MLD Configuration in the IP Multicast 

volume.  

 

When a host leaves an IPv6 multicast group, the host sends an MLD done message to the multicast 

router.  

When the switch receives an MLD done message on a dynamic member port, the switch first checks 

whether a forwarding table entry for the IPv6 multicast group address in the message exists, and, if one 

exists, whether the outgoing port list contains the port.  

z 

If the forwarding table entry does not exist or if the outgoing port list does not contain the port, the 

switch discards the MLD done message instead of forwarding it to any port. 

z 

If the forwarding table entry exists and the outgoing port list contains the port, the switch forwards 

the MLD done message to all router ports in the native VLAN. Because the switch does not know 

whether any other hosts attached to the port are still listening to that IPv6 multicast group address, 

the switch does not immediately remove the port from the outgoing port list of the forwarding table 

entry for that group; instead, it resets the aging timer for the port. 

Upon receiving an MLD done message from a host, the MLD querier resolves the IPv6 multicast group 

address in the message and sends an MLD multicast-address-specific query to that IPv6 multicast 

group address through the port that received the MLD done message. Upon receiving the MLD 

multicast-address-specific query, the switch forwards it through all the router ports in the VLAN and all 

member ports for that IPv6 multicast group, and performs the following to the receiving port:  

z 

If any MLD report in response to the MLD multicast-address-specific query is received on the port 

(suppose it is a dynamic member port) before its aging timer expires, this means that some host 

attached to the port is receiving or expecting to receive IPv6 multicast data for that IPv6 multicast 

group. The switch resets the aging timer for the port.  

z 

If no MLD report in response to the MLD multicast-address-specific query is received on the port 

before its aging timer expires, this means that no hosts attached to the port are still listening to that 

IPv6 multicast group address. The switch removes the port from the outgoing port list of the 

forwarding table entry for that IPv6 multicast group when the aging timer expires.